Hitachi A118186

Mounted on the 1994 camcorder right next to a board label of Y/C is a mini PCB.  On the underside is mounted  a 64 pin A118186 chip with an Hitachi logo.

Y/C is short for Luminance and Chrominance, luminance is the brightness signal of a greyscale image, and chrominance is how the colour signal is superimposed on it for colour imaging.  I do not know what the A118186 does as I could find no datasheet but will guess that it is a luminance & chrominance processor.

Here are the die marks confirming the Hitachi logo on the package

A118186 Die Photo

And here is the rather splendid die photo of a fairly large chip (For 1994) measuring 5.78 x 5.24 mm

Hitachi A118186 die photoNow this is something of a rare beast, and certainly not something you would see today, it is an LSI Bipolar logic chip!

In the 80’s & 90’s Bipolar devices were preferred when you needed high speed functions, as Bipolar devices switched faster than MOSFETS (At that time when MOSFET gate lengths where 0.5μm or larger).  The problem with Bipolar transistors is that even small ones consumed a lot of current (Typically 0.5mA is not unusual.)  Creating large scale integration devices with Bipolar transistors needed careful design and still consumed high power.  So it is even more surprising this is on a board powered by a battery!

Here is a close up of logic area.  You can see the part has two layers of (Aluminum) metal. There are two sizes of rectangular Bipolar layouts, it looks like they have 1x, 2x and 3x transistors where the dimensions and current draw would scale with the emitter width.

You can see a section of the chip in the middle where the transistor layout is significantly more dense.  Here is a close-up from that region
This might be some sort of storage/memory array as between blocks of very dense Bipolars are several rows of horizontal interconnect, and each Bipolar block is also accessed with dense vertical interconnect.

Now as a bonus on top of the mini PCB is a small 8 pin chip just labelled 8838. And a week 9 1994 date code for when it was packaged.

8838 Secondary Die Photo

Here is the 2.4mm x 2mm 8838 dieHitachi 8838 die photoIt’s a small CMOS die with 5μm minimum dimensions and a single metal layer.  Obviously it is a performing a support function to the A118186 chip.  Not having a datasheet for the A118186 I don’t know what function.  You can clearly see two channels with significant symmetry from the right and left side of the die.

The racetrack features in the middle are (to me) very unusual – I haven’t seen anything like them before.  Here is a close-up image.  They appear to have alternating gates from two levels of polysilicon. I suspect they may be a shift register where bits are clocked through from one end to the other.

A clue may be in the text in the middle of the die between the blocks


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